[
    {
        "dataset_name": "pretrain",
        "task_name": "mlm",
        "weight": 1.0,
        "path": "/path/to/dataset",
        "transforms": [
            {
                "answer": "$answer",
                "document": "$source"
            },
            {
                "answer": "$answer",
                "query": "$source"
            },
            {
                "answer": "$answer",
                "input": "$source"
            }
        ]
    }
]